Experimentally induced infections of European eel Anguilla angutila with Anguillicola crassus (Nematoda, Dracunculoidea) and subsequent migration of larvae

Abstract

Migration pattern of third-stage Anguillicola crassus larvae, and pathogenesis of the lesions induced by third-stage larvae, was investigated in European eel Anguilla anguilla L. Young elvers (l g) were fed infected Paracyclops fimbriatus (Copepoda). Eel samples were collected and examined histologically at varying intervals during the 6 mo post-infection period. Third-stage larvae (L-111) migrated directly through the intestinal wall and body cavity to the swimbladder within 17 h postinfection. L-IV larvae were detected 3 mo post-infection, and immature adults were detected within 4 mo post-infection. The parasites occasionally showed aberrant migration paths. Pathological effects caused by the parasite were less severe after experimentally induced infections than those detected in some natural infections.